In modern bicycles, in particular in high-performance ones, it is becoming increasingly common to use on-board equipment that uses oleo-hydraulic controls. This is the case for example of disc braking systems, in which the force necessary to obtain adequate braking by the closing of the calipers on the discs is too high to be exerted with the usual cable systems, controlled by the cyclist's hands. With these braking systems, therefore, the force exerted by the cyclist's hand is transferred to an oleo-hydraulic group; more specifically, a piston is actuated that places oil inside a cylinder under pressure. The pressurised oil is then transferred through suitable tubes to the brake calipers, to obtain braking.
In addition to disc braking systems, other equipment could also advantageously use an oleo-hydraulic control.
It is known to associate the oleo-hydraulic groups to the bicycle by fixing them to a part thereof, like for example the frame or the handlebars; the brake lever actuates a cable that from the lever goes to the piston, which in turn places oil in the cylinder under pressure. In this way, however, oleo-hydraulic groups can be a hindrance to the cyclist while the bicycle is in use, due to their bulk, as well as making its aesthetic appearance less pleasing.
It is also known to associate the oleo-hydraulic controls directly to the brake lever; in these controls, the brake lever more or less directly actuates the piston that places oil in the cylinder under pressure, and this is located in the immediate vicinity of the brake lever. In these controls, the bulk can be less and less inconvenient to the cyclist with respect to controls with oleo-hydraulic groups applied to other parts of the bicycle.
The Applicant has realised, however, that oleo-hydraulic controls directly associated to the brake lever do not have problems of bulk only if the size of the cylinders is contained within fairly low limits; in practice, the designer is forced to use very small cylinders, which can reduce braking performance, or to accept a bulk that is still inconvenient.
The Applicant has thus thought to make an oleo-hydraulic control that does not have problems of bulk for the cyclist or size constraints for the designer.